#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <math.h>
int main()
{
	int a[10000], n;
	double sum1 = 0, sum2 = 0;
	scanf("%d", &n);

	for (int i = 0; i < n; i++)
	{
		scanf("%d", &a[i]);
		sum1 += a[i];
	}
	sum1 = sum1 / n;

	for (int i = 0; i < n; i++)
		sum2 += pow(a[i] - sum1, 2);

	sum2 = sqrt(sum2 / n);
	printf("%.5lf", sum2);
	return 0;
}